Plant Reproduction and Breeding

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Transcript Plant Reproduction and Breeding

Plant Reproduction and
Topic #3
Selective Breeding
 Selective breeding means that people have chosen
specific plants with particular characteristics and
encouraged these plants to reproduce
 Example: Canadian researchers were responsible
for developing canola (Canadian + oil). The original
plant was rapeseed, but they selectively bred
rapeseed plants that produced a good-tasting oil.
Work continues with breeding to produce crops that
are resistant to disease, drought and even chemicals
Genetic Modification
 Plant scientists now have the ability to make
changes to plants by going inside a plant cell and
changing some of its material (genetic code)
 They can take genes and combine them with genetic
material from other plants. This is put back into the
plant and is used to create a new plant.
 This process is called genetic modification, but is
more commonly called genetic engineering
Vegetative (Asexual)
 Asexual reproduction occurs
when a “parent” plant grows
new plants from its roots,
stems or leaves.
 Grafting is when you take a
branch from one tree and
attach it to another, where it
will grow and thrive
 Layering is when a branch
from a plant is bent down to
the ground and covered with
soil. Roots will grow from the
buried stem and eventually a
new plant will grow
Veg. Rep. (cont)
 Commercial growers
will often use cuttings
(small sections of leaf
and stem cut from a
parent plant) to grow
new plants
 This guarantees that the
new plant will be just
like the parent
Sexual Reproduction
 Many trees produce male and female cones.
 Larger female cones contain ovules (eggs)
 Smaller male cones contain pollen grains with
 Wind carries pollen grains to the female cones,
although most never reaches them
 You’ve probably seen wafts of yellowish pollen in
the air
Cones (cont)
 Once the pollen reaches the female cones, the eggs are
fertilized and a tiny seed begins to grow
 This process is called pollination
 Female cones then
release their seeds,
which will get carried
elsewhere, buried and
will grow a new tree
 Flowers are usually bright coloured to attract insects
and other animals who will help pollinate the plant
while feeding on the plant’s nectar
 Flowers may also have strong scents to guide
insects and animals at night
 Flowers that aren’t as “showy” often depend on the
wind to spread their pollen instead
Parts of a Flower
 Pollination can happen in several ways
1) Some plants like barley, self-pollinate – the sperm
fertilizes the eggs in the same plant
2) In cross-pollination, the eggs of one plant are
fertilized by the sperm from another plant
3) Artificial pollination can also be used where
humans are breeding specific plants together for
their traits – selective breeding
Disgusting Fruit
 The last time you ate a piece
of fruit, did you realize you
were eating the growing
ovary and embryo of the
plant? Its one purpose is to
protect the developing seeds
of the plant until they are
Seed Dispersal
 Tumbleweeds
 Dropping coconuts
 Fruit-eating birds
 Sticky burrs
 Sticky pitch or sap
 Dandelion “umbrellas/parachutes”
 Once the seed has been dispersed and reaches the
ground, it stays inactive until the growing condition
are right
 Germination is the development of the seed into a
new plant